1. Technical Field
The present invention relates to a gas shower plate for use with plasma processing apparatuses, which is included in a plasma processing apparatus for performing plasma processing to a processing object such as a wafer or the like.
2. Description of the Related Art
As apparatuses for performing surface treatment of processing objects such as wafers or the like, there have been known plasma processing apparatuses. A plasma processing apparatus operates to produce plasma under a reduced-pressure atmosphere to allow a surface of a processing object to be subjected to etching processing or the like by physical and chemical actions of the plasma. Plasma is generated by applying a high-frequency voltage to an upper electrode or lower electrode while the internal pressure within a sealed processing chamber of the plasma processing apparatus is reduced to a specified pressure with a plasma-generation gas (hereinafter, referred to simply as ‘gas’) fed thereto.
For such plasma processing, it is desirable in some cases to generate high-density plasma depending on the aim of processing. For example, in plasma etching targeted for silicon substrates such as wafers or the like, a process of uniformly spraying and feeding a relatively high-pressure gas to a surface of a silicon wafer is used with a view to improving the processing efficiency.
Known gas shower plates which are parallel-plate electrode members suited for such plasma processing include a gas shower plate formed of a gas-permeable porous plate which is a sintered body of ceramic particles (see, e.g., Japanese unexamined patent publication No. 2002-231638 A, JP 2003-7682 A and JP 2003-282462 A). With the use of a gas shower plate formed as such a porous plate, it becomes possible to uniformly generate high-density plasma so that a stable plasma processing is carried out with high etching efficiency.